Easter procrastination

I'm supposed to be doing my homework right now. But it's not due until Tuesday, so technically I don't have to do it tonight...

But I always have a hard time concentrating when I'm in the lab, and I have my orchestra dress rehearsal tomorrow night. So it would probably be better to do it now.

Wait, I know -- if I do it in blog format, maybe I can trick my brain into thinking I'm not actually working!

Also, I'm not going to make any effort to make it sound good...

Okay, here goes:
1. Where on Mars should we look for extant life?

I'm just throwing this out there, but...how about underneath where they found all that methane in the atmosphere? It's probably not biogenic, but you won't know unless you look.

How would you look for it?

Uh...well it would have to be in the subsurface. So I guess we could drill down and take out a soil sample.

Then what?

Uh...look...for...life...in...it.

That's not very specific.

No kidding. Okay, well you could look for morphological stuff. This would probably involve sample return. And/or you could analyze the carbon content using mass spec.

Which would tell you what?

Well they would need to make some kind of biomass, right? Even methanogens need higher order carbon molecules.

So does thermal decomposition of rocks.

Fine. But maybe you could also look for enrichment in light carbon. Most of the carbon on Mars should be heavy due to escape.

2. Where on Mars would you look for extinct life?

Somewhere that clearly had water.

That's a lot of places.

Yup. Maybe Meridiani Planum then, since we talked about that in class. I need to read that paper to see if one place there is better than another (it's a bigass planum). We should probably go somewhere with hematite, which is a pretty good indicator of water.

Okay, well assuming you figure out where specifically to go, how do you look for life there?

Well this would not necessarily be in the subsurface, but it would probably have been covered by dust (which could then become rock), so you'd probably still have to dig a little bit. Then I guess you could do the same stuff that you did for the extant life. You'd probably be looking more for stromatolites than intact cells.

Well this makes your first approach seem kind of dumb. Shouldn't there be a difference between the treatment of things that are living and things that are dead?

Probably. And now I'm not sure that living organisms would survive the trip back to Earth.

How do you know that Earth life is alive?

Well, you can try to grow it. You can stain it for ATP production.

You can look for its DNA. You can look for RNA, or any number of proteins. But actually the presence of these things doesn't mean it's alive, but that it was probably alive once. Also, these things might not be a factor in Mars life.

I kind of like the idea of checking for a decrease in things the org eats, and an increase in the thing it produces. If you put methanogens in an environment with labeled CO2, and then see labeled CH4, that might mean something.

I don't think it would be very easy to confirm that something is living at the time from a remote location -- you have to either send an astrobiologist or somehow get the thing back to Earth alive. But maybe it will be sufficient to start by going somewhere where extant life is thought to be, show that is was at least alive at one point, and then go back later and do these more difficult procedures. Yeah, I think that's probably the way to go.

And now to make this coherent...

Addendum: Are there photosynthetic methanogens? Should we look for green stuff? Or purple stuff?